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| UPSonNet NewsLetter May 2010 |
UPSonNet
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Best UPS Battery Technology
Lead acid is the dominant UPS battery technology; still performance drawbacks and ecological
unfriendliness invite exploring alternate solutions.
Manufacturers of lead acid battery, since technology introduction in the 19th century, have
constantly improved energy density and reduced maintenance needs by various means, including
development of sealed VRLA batteries. These steps enabled manufacturers to present the most cost
effective solutions for rechargeable batteries, to gain market share and compete with alternate
products, particularly for UPS applications.
The lead acid technology suffers however from numerous drawbacks, such as poor temperature
performance, limited battery life which requires, as indicated in our April newsletter titled Impact
of Backup Batteries on UPS Reliability, frequent need to monitor and replace batteries, limited
discharge cycles, and poor energy per weight ratio, particularly when short discharge times are
required. In addition, recent global ecological and health oriented concerns, calling for eliminating
toxic materials, and Get The Lead Out, all foster seeking other solutions.
General Electric (GE) has announced in May 2010 its Durathon Sodium-Metal Halide Battery for
UPS Battery applications. GE's decision to harness the Sodium Nickel battery technology for UPS
backup, may present an alternative that solves most of the mentioned Lead Acid battery problems.
Durathon battery technology is based on know-how of UK's Beta R&D Company which was
acquired by GE in 2007. Durathon will be manufactured in a new battery plant located at
Schenectady, New York, where $ 150 million are invested to build upon this technology.
The sodium nickel chloride battery, known as the ZEBRA battery, was produced and marketed
mainly for various vehicle applications. GE's decision to adopt the technology for critical power
applications will enable it to offer a product with distinct advantages, which may have a
considerable impact on the UPS industry if financially competitive.
The ZEBRA battery utilizes molten sodium aluminumchloride (NaAlCl4), as the electrolyte. The
negative electrode is molten sodium. The positive electrode is nickel in the discharged state and
nickel chloride in the charged state. A sodium-conducting β-alumina ceramic is used to separate the
liquid sodium from the molten electrolyte. Since the liquid electrolyte freezes at 157 °C, normal
battery operational temperature range is 270 °C to 350 °C. The cells are therefore heated and
contained in a thermally insulated box.
When not in use, ZEBRA batteries are typically left under charge so that they will remain molten and
be ready for use. Otherwise preheating is needed before the batteries can be put to use.
To observe the pros and cons of the Zebra technology, when compared to lead acid UPS battery,
we present comparison of main specifications of a UPS battery bank from main Battery
manufacturer to equivalent Zebra battery.
Following table compares, Enersys, Powersafe 240V battery bank comprising 24 series connected
12V62F Front terminal 62 AH, 10 year rated batteries, to MES-DEA, Zebra 64AH: Z5-278-ML-64
battery:
Enersys batteries refer to discharge to 1.75V/Cell, unless noted otherwise.
Based on the above table the Zebra Battery offers the following benefits:
- Zebra battery is less sensitive to low voltage discharge. Lead acid battery load should be
disconnected below 1.6 V/cell to prevent battery damage.
- Specific energy offered by Zebra battery is 200% higher than Lead Acid ( 91Wh/kg versus
41Wh/kg).
- Lead Acid battery requires 33% more space (103 Wh/liter versus 137 Wh/Liter).
- The energy of Zebra battery drops only slightly with rate of discharge, whereas potential
energy of Lead acid battery falls dramatically when high discharge rates are required (to
about 50% of rating for 15 minutes discharge).
- Zebra Battery operation isn't influenced by ambient temperature; it is able to work in extreme
environments. Whereas, temperature does influence strongly performance and lifetime of
lead acid battery, practically requiring conditioned environment in most cases, even when
stored.
- Zebra battery offers longer operating lifetime, which is less sensitive to discharge cycles,
and dramatically longer maintenance free shelve life.
Lower discharge current and high system operating temperature form the main drawbacks
associated with Sodium Metal Chloride batteries. Maximum discharge current rating is only 50% of
lead acid and may require bigger batteries for short backup times. The high system temperature
causes wasting power on maintaining battery heat, preheating after storage, and may pose a safety
problem, particularly in hazardous environments.
Proper temperature isolated packaging can probably provide a safe solution. Preheating requirement
is less critical in UPS applications and thermal losses are overridden by the significant advantages. It
remains to be seen, whether the cost of the new batteries for UPS application will be attractive
enough to challenge, the over hundred years old lead acid technology.
UPSonNet Website News
We are now in a process of changing the appearance of our web pages as well as increasing page
width. This allows us to display more information on each page, by adding new items of interest to
our visitors. You will therefore find new information on our web pages, such as UPS guides, and
Mostly Viewed Articles, which were previously published by us on various information channels.
Main site pages such as: Home, News, UPS- Selection, and more, were already redesigned, other
pages should follow during June 2010.
The new design offers also more space for advertising. Most of our current ads are presented by
commercial ad placing companies (including Google), generally unable to correlate relevant ads to
page content.
We would like to treat advertisement as a service to our visitors, by presenting ads correlated with
page content, which inform customers about relevant products and services. We have therefore
decided to offer for a limited time (not more than 30 days) from completing the redesign of website
pages, discounts reducing current prices to 60% of our existing advertising prices, to industry
manufacturers, distributors and service providers.
We will inform the exact date by means of a specific newsletter. However, readers interested to
take advantage of this offer, and interested to display ads on specific pages, as long as these are
available, are welcome to see our advertising information, and letting us know their preferred
interests by sending an e-mail to: advertise@upsonnet.com
If you are not involved in advertising, we would appreciate if you could inform the relevant people
in your organization, or use the above e-mail for informing us the relevant person's contact details.
UPS Industry News
Our editorial topic concerning GE's Durathon batteries seems to be the most interesting UPS news
item published in May 2010. You can read more about it by following the relevant news brief link on
UPSonNet News page.
On the same page you will also find our press release brief titled: UPSonNet Launches UPS
Comparison Guide for Professional Users. The brief and the leading links on the press release,
provide valuable information not found elsewhere, of interest to users looking for Online UPS, to
manufacturers and sellers for comparing their systems to competition and to consultants for finding
the most suitable system for an oriented application.
Remark : Certain links on UPSonNet website are available only to subscribed members. For
Unrestricted access to the entire site please Sign-UP.
We welcome remarks on any Newsletter issue. Please e-mail to: denis@upsonnet.com
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